Dear Marco,
>
> Hi all,
>
> Apologies if the question does not make sense...
>
> What does actually happen to b0s when running eddy? Are they only involved in the correction of motion?
>
> I would like to append to my real b0s, additional volumes. These are non diffusion-weighted EPI volumes (acquired with almost identical readout of dwi) with very different contrast (e.g. Inversion Recovery data at different inversion times). I would like to give this fake 4D volume (real b0 + "fake" b0 + dwi) to eddy. Does anyone know if there could be a bad interplay between the real dwi dataset and the additional volumes I add (especially because the "fake" b0 will have quite a different contrast compared to the real b0) ?
that is an interesting question. I can see the logic in wanting to “piggy-back” another scan onto the correction to ensure it is processed in the same way and in the same space.
Unfortunately I cannot think of a simple way of achieving that with the current version of eddy. At present it would cause a problem with the alignment of the b0 data (the real b0 data) if you were to label these as b0. And it would cause a problem with the alignment of the diffusion weighted data if you were to label them as diffusion weighted.
Internally the b0 and the dwi processing is quite separate, and the information passed between the two does not rely on any assumptions about the contrast in either. It would be possible to add another category that is treated in the same way as the b0 volumes, but kept separate from the actual b0s. But that would mean some coding.
Jesper
>
> Thanks a lot
> Marco
>
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